Anti-ATF4 (aa 171-270) polyclonal antibody

Exercise is an effective way to prevent osteoporosis, but its mechanism remains unclear. MicroRNAs (miRNAs) play an essential role in bone metabolism. Recently, mechanical loading was reported to induce changes in miRNA expression in osteoblasts. However, the role of miRNAs in bone under exercise and its underlining mechanisms of action still remain unknown. MiR-214 was reported to regulate the process of osteogenesis and is considered a biomarker of osteoporosis. In this study, we aimed to investigate whether exercise could induce changes in miRNA expression in bone and to study the effects of miR-214 on mechanical loading-induced osteogenesis in osteoblasts. The results showed that miR-214 was down-regulated in both tibia from C57BL/6 mice after exercise in vivo and in osteoblasts after mechanical strain in vitro. Mechanical strain could enhance the ALP activity, promote matrix mineralization, up-regulate the expression of osteogenic factors such as ATF4, Osterix, ALP and beta-catenin, and down-regulate RANKL and RANK expression. Over-expression of miR-214 not only inhibited the expression of these osteogenic factors but also attenuated mechanical strain-enhanced osteogenesis in osteoblasts. Collectively, our results indicated that miR-214 could attenuate the osteogenic effects of mechanical loading on osteoblasts, suggesting that inhibition of miR-214 may be one of the ways in which exercise prevents osteoporosis.

Background: Withaferin A is a functional ingredient of a traditional medicinal plant, Withania somnifera, which has been broadly used in India for protecting against chronic diseases. This bioactive steroidal lactone possesses multiple functions such as anti-oxidation, anti-inflammation, and immunomodulation. Chronic kidney disease (CKD) is one of the major health problems worldwide with the high complication, morbidity, and mortality rates. The detailed effects and underlying mechanisms of withaferin A on CKD progression still remain to be clarified. Purpose: We aimed to investigate whether withaferin A treatment ameliorates the development of renal fibrosis and its related mechanisms in a CKD mouse model. Methods: A mouse model of unilateral ureteral obstruction (UUO) was used to mimic the progression of CKD. Male adult C57BL/6J mice were orally administered with 3 mg/kg/day withaferin A for 14 consecutive days after UUO surgery. Candesartan (5 mg/kg/day) was used as a positive control. Results: Both Withaferin A and candesartan treatments significantly ameliorated the histopathological changes and collagen deposition in the UUO kidneys. Withaferin A could significantly reverse the increases in the protein levels of pro-fibrotic factors (fibronectin, transforming growth factor-beta, and alpha-smooth muscle actin), inflammatory signaling molecules (phosphorylated nuclear factor-kappa B-p65, interleukin-1 beta, and cyclooxygenase-2), and cleaved caspase-3, apoptosis, and infiltration of neutrophils in the UUO kidneys. The protein levels of endoplasmic reticulum (ER) stress-associated molecules (GRP78, GRP94, ATF4, CHOP, phosphorylated eIF2 alpha, and cleaved caspase 12) were increased in the kidneys of UUO mice, which could be significantly reversed by withaferin A treatment. Conclusion: Withaferin A protects against the CKD progression that is, at least in part, associated with the moderation of ER stress-related apoptosis, inflammation, and fibrosis in the kidneys of CKD. Withaferin A may serve as a potential therapeutic agent for the development of CKD.